#include <iostream>
using namespace std;

class A {
  private:
    int a;

  public:
    A(int m) : a(m) {}
    void Show() const { cout << a << endl; }
};

class B : A {
  private:
    int b;

  public:
    B(int m, int n = 0) : A(m), b(n) {} // 初始化数据成员b的值为n
    void Show() const {
        A::Show();
        cout << b << endl;
    }
};

int main() {
    B obj(8);
    obj.Show();

    return 0;
}
